1. Field of the Invention
This invention relates to fluid couplings and more particularly to a push-pull or breakaway type coupling usable for example between a tractor and an implement towed therebehind, in which disconnection of the coupling can be made by a mere pulling action.
2. Description of the Prior Art
It is commonplace to employ the breakaway type coupling between, for example, a tractor and an implement towed thereby for automatic disconnection in the event of either intentional or accidental mechanical disconnection of the towed implement. It is further well known in the art to provide internal valves in the male and female interfitting elements of the breakaway connector so as to prevent spillage or loss of fluids or the like. Prior art devices have been successful in this regard, however with the need for larger coupling devices in association with larger towed implements and in order to provide adequate levels of fluid or material flow it has become necessary to provide a relatively simple mechanism for effecting the connect and disconnect function without unduly increasing its size. Further, because of the high mass of hose which typically is joined to the halves of the coupler device, much higher levels of disconnect forces are being encountered, in other than the breakaway situation.
In couplers which are sized for one and one quarter inch hose, the weight of the hose and the associated hose inertia and the like have resulted in a requirement for preventing disconnections for forces on the order of up to one hundred pounds. In most conventional couplers, connecting and disconnecting forces are approximately on the same level, thus imposing a burden on coupling which is often difficult to achieve. It would be preferable to tailor the levels of connect and disconnect forces for the particular needs and to have a simplified coupling structure, than to have some accomodation therebetween in an effort to reduce the overall size of the coupling elements.
Similar push-pull and breakaway type couplings are known in the art, none of which provide a desired advantageous configuration for large size coupling devices.
Thus, in U.S. Pat. No. 3,567,255 there is shown a breakaway coupling having an interior valving for preventing loss of fluid upon uncoupling. Locking and unlocking forces are provided by an annular overcenter spring, however, there is no teaching of reduction of coupling force in a mechanism which provides a desired high level of uncoupling force.
In U.S. Pat. No. 3,674,051 there is described a coupler using plural compression springs which are selectively utilized during coupling and uncoupling operations. This coupler however is especially suited for actuation when pressure is existent in the system. It relies on the use of springs having different spring rates in conjunction with a relatively complex mechanism including plural detent devices, a structure which is inordinately complex and bulky in the large size range of couplers.
U.S. Pat. No. 3,964,771 describes a push-pull connector which provides different levels of coupling and uncoupling force, this being accomplished by way of a radially compressible annular spring and cooperating ramp surfaces, a structure likely not well suited in the rugged high force level environment.